The Weather Network – The giant A-68a iceberg discharged 152 billion tons of fresh water into the ocean
Sunday, January 30, 2022, 3:12 p.m. – Changing salinity levels and impacts on plant and animal species are some of the concerns of scientists after the A-68a “megaberg” nearly crashed on the island of South Georgia.
The massive A-68a iceberg was slowly drifting across the Southern Ocean last year, traveling 4,000km from its home in Antarctica, and was the largest iceberg on the planet at the time. Its disappearance came after the warm sea gradually thawed, a process that released 152 billion tonnes of fresh water, and alarmed scientists who predict there could be serious impacts on local ecosystems.
A study, published in Environmental remote sensing, says this “megaberg” broke away from the Larsen-C ice shelf in July 2017 and melted over a three-month period beginning in late 2020, disappearing completely in early 2021.
The remains of A-68a, along with other large pieces that also broke away from A-68, January 11, 2021 near South Georgia Island. (NASA Earth Observatory image by Lauren Dauphin, using VIIRS data from NASA EOSDIS LANCE, GIBS/Worldview and the Suomi National Polar-orbiting Partnership)
A-68a initially measured 5,719 square kilometers and was the sixth largest iceberg ever recorded by satellite. The amount of fresh water released, equivalent to 61 million Olympic swimming pools, eventually engulfed the subantarctic island of South Georgia, which has a delicate ecosystem due to its remote location.
South Georgia is located in one of the world’s largest marine protected areas and is home to millions of king and gentoo penguins, which many scientists feared might be in the way of the megaberg. Flightless birds were spared, but the study indicates that many plant and animal species could suffer from the dilution of ocean water and changing salinity levels.
Colony of king penguins (Aptenodytes patagonicus) on Salisbury Plain on South Georgia Island. The king penguin is the second largest species of penguin, smaller, but somewhat similar in appearance to the emperor penguin. (Janet K Scott/Moment/Getty Images)
Some impacts melting icebergs have on their environment include introducing cold meltwater into regions of relatively high salinity, scraping the seafloor, and destabilizing the mother ice shelf as they break away. . Icebergs also carry nutrients, such as iron, in the debris they carry, which can alter many ocean properties and plankton populations.
“This is a huge amount of meltwater, and the next thing we want to know is whether it had a positive or negative impact on the ecosystem around South Georgia,” said Anne Braakmann-Folgmann, lead author of the study and Ph.D. candidate at the School of Earth and Environment at the University of Leeds, in a press release.
The closest recorded distance between A-68a and South Georgia was 62 km on December 15, 2020 and researchers say that although it did not wash up on the seafloor, other icebergs could do so at the future. Icebergs dragging along the seafloor damage the wildlife that live there, which can have cascading effects on animals in the food chain, including birds, seals and whales.
The study states that the path taken by A-68a is “a common iceberg path” and that “more research should be conducted to investigate the impact of this alteration on marine life around South Georgia.” “.
Thumbnail Credit: Brett Monroe Garner/Moment/Getty Images